The present invention relates to a feeding device for introducing molten steel into twin belt casters employing mold walls which move exclusively in the casting direction, with the feeding device including a tundish which is adjustable in height and which is followed by a tubular, closed pouring body which is movable with respect to the twin-belt caster and is likewise adjustable in height, and has a spout which extends between the mold walls and produces a sealing gap with the mold walls. Of the two members that can be connected together via the pouring body--the twin-belt caster and the tundish--at least the latter is displaceable.
The present invention further relates to a mode of operation for such a feeding device for the introduction of molten steel into twin-belt casters employing mold walls that move exclusively in the casting direction wherein movement of the pouring body establishes a connection, via the pouring body, between the tundish and the twin-belt caster so as to permit casting.
According to present knowledge, at casting speeds around 10 m/minute, steel can be cast into bars having a cast cross section of about 70.times.180 mm only in casters in which the mold walls move along. Attempts disclosed in the past to process steel in such casters at greater casting speeds have not resulted in cast products having sufficiently good metallurgical quality.
Federal Republic of Germany published patent application DE-AS No. 3,009,189 discloses a tubular pouring body which cooperates with a rigid continuous casting mold where the pouring body serves as the feeding device for introducing the molten steel. This pouring body is in immovable connection with a tundish but it can be moved and adjusted in height with respect to the continuous casting mold via the tundish. Sealing of the annular gap between the reciprocating continuous casting mold and the pouring body projecting thereinto is effected by the generation of inductive forces in a magnetic coil which surrounds the exterior of the continuous casting mold and is also effective in the starting section of the continuous casting mold. The drawback of the prior art design is that it can be aligned with respect to the continuous casting mold only by moving and changing the height of the heavy tundish.
In the apparatus disclosed in Federal Republic of Germany laid open patent application DE-OS No. 1,758,960, the tundish is connected by way of a rigid pipe end and via a ball joint, with a rigid continuous casting mold. The movable part of the ball joint forms a short pouring body in the form of a spherical section which is supported by way of its convex surface in the concave countersurface of the pipe end. The frontal surface of the spherical section facing away from the tundish is sealingly held against an annular plate which simultaneously forms the immovable spout of the spherical section. Screws fastened to the tundish serve as pressure elements. The drawback of this known solution is that the only compensatory movement possible is a rotary motion between the tundish and the continuous casting mold. However, during the casting process, the tundish becomes hotter than the continuous casting mold, so that both parts are displaced perpendicularly with respect to one another and thus require automatic height adjustments. Such adjustment is not provided, however, and is not possible at all because of the short structural design of the pouring body.
The present invention is based on the known realization that perfect cast products can be obtained only if the molten steel can be introduced from outside into the space between the moving mold walls of the twin-belt caster without the ingress of air. It must be assured that the molten steel can not flow out of the twin belt caster in a direction opposite to the casting direction and that, in spite of sufficient tightness, the mold walls and the spout of the pouring body will not be damaged.